Transparent sheet material



Patented 1.1,. 5,1932

UNITED STATES PATENT orrica EDQUARD u. mrz or CHICAGO, rumors, ASSIGNOR'ro mam rnonuc'rs 00., A CORPORATION or ILLINOIS TRANSPARENT SHEETMATERIAL No Drawing.

This invention relates to transparent sheet material adapted for use asWrapping for candy boxes, bonbons, flowers and the like.

In my copending application entitled, Transparent sheets and the processof manufacture, Serial No. 10,962, filed Februar 21, 1925, l havedisclosed a method of ma ring transparent sheet material from gelatineand sulphonated castor oil. I have now found that if a glycol, such asethylene glycol, diethylene glycol, or the ethyl ether of (ii-ethyleneglycol is used wholly or partly in place of sulphonated castor oil, avery satisfactory, relatively non-hygroscopic sheet is obtained. 1 havefurther found that a small amount of sulphonated castor oil or othergrease dispersing agent is practically essential for the formation of asatisfactory sheet.

lhis invention has, therefore, for one of its objects to provide animproved composition for forming relatively non-hygroscopic trans parentsheet material from. elatine and a glycol, together with a suite legrease dispersing agent.

Other and further important objects of this invention will becomeapparent from the disclosures in the following description and appendedclaims, which set forth a preferred form of my invention.

The proportion of glycol to gelatine may be varied over a considerablerange, depending upon the qualities desired in the sheet. Gelatinesheets, as is well-known, are extremelyhygroscopic and fragile, and aresubject to great physical chan e with varying atmospheric conditions.lycol, including 'certain of its homologs, serves as a softening agentfor the gelatine and renders it substantially non-hygroscopic andpliable.

Ordinarily, the percentage of glycol in the finished sheet material willrange between limits of 5 and 60%. Below 5% the resulting sheets wouldbe too hard and brittle, and above 60% they would be too soft and lackcoherence. A more satisfactory range would be from 15 to 40% of glycoland the balance largely gelatine. A part of the glycol content may bereplaced by sulphonated castor oil, an in fact, it is preferable to adda small quantity of sulphonated castor oil in order Application filedAugust is. 1927. Serial at. 21am.

hyde or chrome salts, may be added to inv crease the insolubility of thesheets.

1 prefer to use a composition containing on a dry basis about 25% of anethylene glycol mixture, 70% of gelatine and about 5% of 40%formaldehyde. The ethylene glycol mixture preferably comprises ethyleneglycol, 30% glycerine and 10% sulphonated castor oil (8% sulphonated).Ordinarily, glycerine is very objectionable on account of itshygroscopic properties, but in combination with glycol, it appears tolose these PI'OP'. erties. lln order to obtain a clear white transparentsheet, it is usually advisable to add a small quantity of a bluedyestufi', such as alizarine sapphirol. For obtaining colored sheets,larger quantities of dyes maybe used the same as in dyeing gelatinesheets.

ln'my process of manufacture, the glue is first soaked in four times itswei ht of cold water for at least six hours-and t en melted at 115 F.The ethylene glycol mixture is diluted and then added to the gelatinesolution with agitation, the temperature being maintained between 100and 120 F. To counteract the yellow cast in the natural sheet, about0.5% of alizarine sapphirol by weight of the dry gelatine composition,is

added to the solution. A small quantity ofa tanning agent may be addedif desired. The mass is then diluted with soft water at 120 F. to theviscosity required to give the desired sheet. The sheet is preferablyformed on an endless belt, such as described in my application entitled,Surface for forming transparent paper, Serial No.

11,335, filed February 24,1925. The belt relatively non-hygroscopic andunafiected glycol, and a grease dispersiii I I 4. Transparent sheetmateria comprising by climatic conditions. I v

The gelatine used should be glue of the highest quality free frompreservatives, especially zinc su phate. The sulphonated oil, If any isused, 1s preferably castor' oil that has been sulphonated so as tocontain be-. tween 4: and 10 o by weight of the sulphonic acid radicalS0,), The sulphonated oil should be thoroughly Washed and neutralizedwith sodium or potassium hydroxide. An ammonia-neutralized oil is notsatisfactory, as it produces a milky sheet. In place off ethylene glcol, (ii-ethylene glycol or the mono ethyl ether of di-ethylene glycolbe substituted.

I am aware that many changes may be made and numerous details of theprocess may be varied through a wide ran c with out departing from theprinciples this invention and I, therefore, do not purpose limiting thepatent granted hereon, othprwise than necessitated by the prior art.

I claim as my invention:

1. Transparent sheet material, comprising gelatine, a water solubleparafiin glycol, and a ase dispersing agent.

2. ransparent sheet material, comprising gelatine, ethylene glycol, anda/grease dispersing agent.

v 3. Transparent sheet material, comprising 40 to 95% of gelatine, 60 toof ethylene agent.

about of a mixture containing ethylene lycol, glyoerine and sulphonatedcastor oil, 0% of gelatine and 5% of a tanning agent. 5 A selfsustaining transparent s set, comprised largely of gelatine and ethyleneglycol,- said s eet being relatively non-hygroscopic and flexible.

, a tanning a 6. A self sustaining transparent sheet, comprised of to ofgelatine and 40 to 15% of an ethylene glycol mixture, con= tainingsulphonated castor oil, glycerine and '7. A sel sustaining transparentsheet,

comprised largely of gelatine and ethylene gl col, and re ativelysmaller quantities of en honated castor 011 and'a tanning agent.

testimony whereof I have hereunto subscribed my name.

r EDOUARD M. KRATZ.

